close in vs tuck

close in is not a noun while tuck is a noun.

Word	Noun	Adjective	Verb	Adverb
close in	No	No	Yes	No
tuck	Yes	No	Yes	No

As verbs, tuck is a hyponym of close in; that is, tuck is a word with a more specific, narrower meaning than close in:

close in (noun)	tuck (noun)
	a narrow flattened pleat or fold that is stitched in place
	a straight sword with a narrow blade and two edges
	(sports) a bodily position adopted in some sports (such as diving or skiing) in which the knees are bent and the thighs are drawn close to the chest
	eatables (especially sweets)

close in (verb)	tuck (verb)
surround completely	fit snugly into
advance or converge on	make a tuck or several folds in
	draw together into folds or puckers